Non-Disruptive Eye Scan for Data Recovery Units Based on Oversampling

1. A data recovery unit, comprising: a phase locked loop configured to receive data samples and generate an output; a first sample selector coupled to the phase locked loop, wherein the first sample selector is configured to receive the data samples and the output of the phase locked loop; and an eye scanner coupled to the phase locked loop, wherein the eye scanner comprises a second sample selector coupled to the phase locked loop via a first horizontal shift module, a first XOR unit having a first input coupled to an output of the first sample selector and a second input coupled to an output of the second sample selector, and a first accumulator coupled to the first XOR unit.

2. The data recovery unit of claim 1 , wherein the phase locked loop comprises: a phase detector; a low pass filter coupled to the phase detector; and a numerically controlled oscillator coupled to the low pass filter; wherein the phase detector is configured to receive the data samples and an output of the numerically controlled oscillator.

3. The data recovery unit of claim 1 , wherein the first horizontal shift module is configured to provides a first phase shift.

4. The data recovery unit of claim 1 , wherein the eye scanner is fully synchronized to one single clock with other components of the data recovery unit.

5. The data recovery unit of claim 1 , wherein the data recovery unit is portable across different digital architectures.

6. The data recovery unit of claim 1 , wherein a frequency of the first sample selector to a frequency of a line rate of the data recovery unit is fractional.

7. The data recovery unit of claim 1 , wherein a frequency of the second sample selector to a frequency of a line rate of the data recovery unit is fractional.

8. The data recovery unit of claim 1 , wherein the eye scanner further comprises: a third sample selector configured to receive the data samples, wherein the third sample selector is coupled to the output of the phase locked loop via a second horizontal shift module.

9. The data recovery unit of claim 8 , wherein the second horizontal shift module is configured to provide a phase shift that is different from a phase shift provided by the first horizontal shift module.

10. The data recovery unit of claim 8 , wherein the eye scanner further comprises: a second XOR unit having a first input coupled to an output of the first sample selector and a second input coupled to an output of the third sample selector; and a second accumulator coupled to the second XOR unit.

11. A data recovery unit, comprising: a phase locked loop configured to receive data samples and generate an output; a first sample selector coupled to the phase locked loop, wherein the first sample selector is configured to receive the data samples and the output of the phase locked loop; and an eye scanner coupled to the phase locked loop, wherein the eye scanner comprises a second sample selector coupled to the phase locked loop via a first horizontal shift module; wherein the phase locked loop comprises a phase detector, a low pass filter coupled to the phase detector, and a numerically controlled oscillator coupled to the low pass filter, and wherein the phase detector is configured to receive the data samples and an output of the numerically controlled oscillator; and wherein the numerically controlled oscillator comprises a summation module coupled to the low pass filter; and a n-bit register coupled to the summation module, and wherein the summation module is configured to receive an output of the low pass filter, an output of the n-bit register, and a center frequency value.

12. The data recovery unit of claim 11 , wherein the center frequency value is configured to control a line rate at which the data recovery unit operates.

13. A method performed by a data recovery unit, comprising: receiving data samples using a phase locked loop; generating an output by the phase locked loop based at least in part on the data samples; processing the output of the phase locked loop, using a first sample selector, to obtain a data recovery unit output; transmitting the output of the phase locked loop to a second sample selector through a first horizontal shift module that provides a first phase shift to the output of the phase locked loop; and comparing an output of the first sample selector to an output of the second sample selector.

14. The method of claim 13 , wherein the act of comparing is performed by a XOR unit to identify bit errors.

15. The method of claim 14 , further comprising accumulating a number of the bit errors.

16. The method of claim 13 , further comprising determining a feature of an eye based on a result from the act of comparing.

17. The method of claim 16 , wherein the feature comprises a width of the eye.

18. The method of claim 16 , wherein the feature comprises an openness of the eye.

19. The method of claim 13 , further comprising: transmitting the output of the phase locked loop to a third sample selector through a second horizontal shift module that provides a second phase shift to the output of the phase locked loop; and comparing an output of the first sample selector to an output of the third sample selector.